I. Field of the Invention
The present invention relates to medical valves through which fluid may be injected into or withdrawn from a patient without requiring use of sharp needles, and more specifically, to such valves in plastic housings sized to mate with a standard ISO or ANSI male luer lock.
II. Description of Prior Art
In many medical situations, it is typical to provide a valve, such as a solid rubber septum on a Y-site or a sample site, which is accessible by a needle piercing through the septum in order to introduce fluids into, or remove blood from, a line coupled to a patient's circulatory system via a catheter inserted into the patient such as through the arm. With such needle-piercable valves, the top of the valve is usually adjacent to or at the top of the valve or site housing and so may be readily wiped clean before each use. While this is advantageous for aseptic purposes, the use of sharp needles presents hazards to medical and other personnel due to the risk of needle sticks which could transmit disease.
In order to reduce or eliminate needle stick problems, it has been proposed to replace the needle-piercable rubber septum with a blunt cannula-accessible valve, such as a rubber piece with a slit septum. The slit septum opens under pressure of a blunt cannula thereagainst to allow the blunt cannula to pass into and through the slit and into communication with the fluid line. The most commonly employed blunt cannulas in the medical field are male luer tapers (an example of which is the distal plastic end of a typical syringe). Many male luer tapers are part of a luer lock and thus also have an internally threaded nut or collar associated therewith to securely lock to a female luer cylinder with lock tabs thereon. The dimensions of the locking nut of standard luer locks conform generally to ISO standards thus dictating the size requirements that must be met to mate with a male luer lock. These size requirements have presented difficulty in providing a needleless valve in a plastic housing.
As will be appreciated, it is most desirable to situate the slit septum valve at the top of the valve housing for aseptic purposes. But this requirement has presented an obstacle to housing the valve in such a manner that a male luer lock is usable with that valve. Desirably, plastics are used in the medical field. So it would be advantageous if the valve housing could be entirely of plastic. But, the plastic housing must be thick enough to withstand the various forces it will encounter in use. Unfortunately, the robber valve piece itself requires so much bulk that difficulties have been encountered in providing a plastic housing about the valve that is sturdy and safe, but yet small enough to fit within the nut of the luer lock to be secured thereto. The requirements on the plastic housing, coupled with the minimum size requirements of the slit valve piece, have thus dictated that the overall size of the plastic housing be larger than the internal diameter of the locking nut of a standard ISO or ANSI male luer lock. With such devices, therefore, it has been necessary to use an adaptor having a blunt needle and lock nut sized to fit the valve housing at one end and a standard female luer cylinder with lock tabs at the other end. The adaptor introduces increased costs, and imposes risk of misuse and error in the field.
Another approach would be to provide split luer wings above the top of the valve so that the valve may still be cleaned, yet the male luer lock nut may be securely locked to the valve housing as shown in U.S. Pat. No. 5,203,775, the disclosure of which is incorporated herein by reference. It is desirable, however, to have the locking interaction of the nut and the valve housing occur along the side of the housing at or below the top level of the valve itself. As mentioned above, however, this has not been found to be readily achievable where the valve housing is made of plastic.
One proposal that does shrink the size of the housing so that the housing may fit within the nut to be locked about the sidewall of the valve housing is to use a thin-walled piece of metal, such as a stamped piece of aluminum with lugs projecting from the side thereof, for the housing. However, the rest of the valve housing, especially the portions that mate to the fluid line, will normally be of plastic making the aluminum/plastic valve housing less desirable from a manufacturing standpoint. Also, medical users tend to prefer plastic for a variety of reasons making the metal/plastic valve housing undesirable from a user standpoint as well.